Mobile device and manufacturing method thereof

ABSTRACT

A mobile device at least includes a first circuit board, a metal frame, an electronic component, a second circuit board, and an RF (Radio Frequency) module. The first circuit board includes a system ground plane. The metal frame at least includes a first portion. The first portion is electrically coupled to the system ground plane and a feeding point. An antenna structure is formed by the first portion and the feeding point. The second circuit board is electrically coupled to the electronic component. The electronic component and the second circuit board are adjacent to the first portion of the metal frame. The RF module is electrically coupled to the feeding point, so as to excite the antenna structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of copending application Ser. No.15/723,336, filed on Oct. 3, 2017, which claims priority under 35 U.S.C.§ 119(e) to U.S. Provisional Application No. 62/437,226, filed on Dec.21, 2016, all of which are hereby expressly incorporated by referenceinto the present application.

BACKGROUND OF THE INVENTION Field of the Invention

The disclosure generally relates to a mobile device, and moreparticularly, to a mobile device and an antenna structure therein.

Description of the Related Art

With the advancements being made in mobile communication technology,mobile devices such as portable computers, mobile phones, multimediaplayers, and other hybrid functional portable electronic devices havebecome more common. To satisfy user demand, mobile devices can usuallyperform wireless communication functions. Some devices cover a largewireless communication area; these include mobile phones using 2G, 3G,and LTE (Long Term Evolution) systems and using frequency bands of 700MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500MHz. Some devices cover a small wireless communication area; theseinclude mobile phones using Wi-Fi and Bluetooth systems and usingfrequency bands of 2.4 GHz and 5 GHz.

In order to improve their appearance, current designers oftenincorporate metal elements into mobile devices. However, the newly addedmetal elements tend to negatively affect the antennas that providewireless communication in mobile devices, thereby degrading the overallcommunication quality of the mobile devices. As a result, there is aneed to propose a novel mobile device with a novel antenna structure, soas to overcome the problems of the prior art.

BRIEF SUMMARY OF THE INVENTION

In a preferred embodiment, the invention is directed to a mobile deviceincluding a first circuit board, a metal frame, an extension radiationelement, an electronic component, a second circuit board, and an RF(Radio Frequency) module. The first circuit board includes a systemground plane. The metal frame includes a first portion. The firstportion is coupled to the system ground plane. A clearance region isformed between the first portion and the system ground plane. The firstportion and the extension radiation element are coupled to a feedingpoint. An antenna structure is formed by the first portion and theextension radiation element. The second circuit board is coupled to theelectronic component. The electronic component and the second circuitboard are adjacent to the first portion. The RF module is coupled to thefeeding point, so as to excite the antenna structure.

In some embodiments, the first portion has a first end and a second end.A first end of the first portion is coupled to a first shorting point onthe system ground plane. A second end of the first portion is coupled toa second shorting point on the system ground plane.

In some embodiments, the clearance region is positioned between thefirst shorting point and the second shorting point.

In some embodiments, the metal frame further includes a second portion,and the extension radiation element is formed by the second portion.

In some embodiments, the first portion substantially has a straight-lineshape.

In some embodiments, the extension radiation element substantially hasan L-shape.

In some embodiments, the extension radiation element has a verticalprojection which at least partially overlaps the second circuit board.

In some embodiments, the extension radiation element has a verticalprojection which at least partially overlaps the clearance region.

In some embodiments, the clearance region substantially has a narrow andlong rectangular shape.

In some embodiments, the mobile device further includes a feedingconnection element coupled between the RF module and the feeding point.

In some embodiments, the second circuit board is further coupled to thesystem ground plane.

In some embodiments, the antenna structure covers a low-frequency bandfrom 2400 MHz to 2500 MHz, and a high-frequency band from 5150 MHz to5875 MHz.

In some embodiments, the first portion is excited to generate thelow-frequency band, and the extension radiation element is excited togenerate the high-frequency band.

In some embodiments, the length of the first portion is equal to 0.5wavelength of the low-frequency band.

In some embodiments, the length of the extension radiation element isequal to 0.25 wavelength of the high-frequency band.

In some embodiments, the electronic component includes a power buttonand/or a volume button.

In some embodiments, the power button and the volume button are disposedat an external side of the first portion.

In some embodiments, the electronic component includes one or moresensing elements.

In some embodiments, the sensing elements are disposed at an internalside of the first portion.

In some embodiments, the first circuit board is a system circuit board,and the second circuit board is a flexible printed circuit board.

In a preferred embodiment, the invention is directed to a method formanufacturing a mobile device. The method includes the steps of:providing a first circuit board, a metal frame, an extension radiationelement, an electronic component, a second circuit board, and an RF(Radio Frequency) module, wherein the first circuit board includes asystem ground plane, the metal frame includes a first portion, and theelectronic component and the second circuit board are adjacent to thefirst portion; coupling the first portion to the system ground plane;forming a clearance region between the first portion and the systemground plane; coupling the first portion and the extension radiationelement to a feeding point, such that an antenna structure is formed bythe first portion and the extension radiation element; coupling thesecond circuit board to the electronic component; and coupling the RFmodule to the feeding point, so as to excite the antenna structure.

In another preferred embodiment, the invention is directed to a mobiledevice including a first circuit board, a metal frame, an electroniccomponent, a second circuit board, and an RF (Radio Frequency) module.The first circuit board includes a system ground plane. The metal frameat least includes a first portion. The first portion is electricallycoupled to the system ground plane and a feeding point. A clearanceregion is formed between the first portion and the system ground plane.An antenna structure is formed by the first portion and the feedingpoint. The second circuit board is electrically coupled to theelectronic component. The electronic component and the flexible printedcircuit board are adjacent to the first portion. The RF module iselectrically coupled to the feeding point, so as to excite the antennastructure.

In another preferred embodiment, the invention is directed to a methodfor manufacturing a mobile device. The method includes the steps of:providing a system circuit board, a metal frame, an extension radiationelement, an electronic component, a flexible printed circuit board, andan RF (Radio Frequency) module, wherein the system circuit boardincludes a system ground plane, the metal frame includes a firstportion, and the electronic component and the flexible printed circuitboard are adjacent to the first portion; electrically coupling the firstportion to the system ground plane; forming a clearance region betweenthe first portion and the system ground plane; coupling the flexibleprinted circuit board to the electronic component; and electricallycoupling the first portion and the extension radiation element to afeeding point, and coupling the RF module to the feeding point, suchthat the first portion and the extension radiation element operate in aplurality of frequency bands.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1A is a back view of a mobile device according to an embodiment ofthe invention;

FIG. 1B is a side view of a mobile device according to an embodiment ofthe invention;

FIG. 2 is a back view of an antenna structure of a mobile deviceaccording to an embodiment of the invention;

FIG. 3 is a diagram of VSWR (Voltage Standing Wave Ratio) of an antennastructure of a mobile device according to an embodiment of theinvention;

FIG. 4A is a back view of a mobile device according to an embodiment ofthe invention;

FIG. 4B is a side view of a mobile device according to an embodiment ofthe invention;

FIG. 5 is a perspective view of a mobile device according to anembodiment of the invention;

FIG. 6 is a perspective view of a mobile device according to anembodiment of the invention;

FIG. 7 is a perspective view of a mobile device according to anembodiment of the invention;

FIG. 8 is a perspective view of a mobile device according to anembodiment of the invention; and

FIG. 9 is a flowchart of a method for manufacturing a mobile deviceaccording to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In order to illustrate the foregoing and other purposes, features andadvantages of the invention, the embodiments and figures of theinvention will be described in detail as follows.

Certain terms are used throughout the description and following claimsto refer to particular components. As one skilled in the art willappreciate, manufacturers may refer to a component by different names.This document does not intend to distinguish between components thatdiffer in name but not function. In the following description and in theclaims, the terms “include” and “comprise” are used in an open-endedfashion, and thus should be interpreted to mean “include, but notlimited to . . . ”. The term “substantially” means the value is withinan acceptable error range. One skilled in the art can solve thetechnical problem within a predetermined error range and achieve theproposed technical performance. Also, the term “couple” is intended tomean either an indirect or direct electrical connection. Accordingly, ifone device is coupled to another device, that connection may be througha direct electrical connection, or through an indirect electricalconnection via other devices and connections.

FIG. 1A is a back view of a mobile device 100 according to an embodimentof the invention. FIG. 1B is a side view of the mobile device 100according to an embodiment of the invention. FIG. 2 is a back view of anantenna structure of the mobile device 100 according to an embodiment ofthe invention (except for the antenna structure, the other elements aretemporarily hidden). Please refer to FIG. 1A, FIG. 1B, and FIG. 2together. The mobile device 100 may be a smart phone, a tablet computer,or a notebook computer. In the embodiment of FIG. 1A and FIG. 1B, themobile device 100 at least includes a system circuit board 110 (orcalled “first circuit board”), a metal frame 120, an extension radiationelement 150, an electronic component 160, an FPC (Flexible PrintedCircuit Board) 170 (or called “second circuit board”), and an RF (RadioFrequency) module 199. It should be understood that the mobile device100 may further include other components, such as a processor, sspeaker, a touch control module, a power supply module, and a housingalthough they are not displayed in FIG. 1A and FIG. 1B.

The system circuit board 110 includes a system ground plane 112, whichis made of a metal material. The system ground plane 112 is configuredto provide a ground voltage. The shapes and sizes of the system circuitboard 110 and the system ground plane 112 are not limited in theinvention, and they may be adjusted to meet different requirements. Themetal frame 120 may be an appearance element of the mobile device 100.The metal frame 120 at least includes a first portion 130. The firstportion 130 may substantially have a straight-line shape. Specifically,the first portion 130 has a first end 131 and a second end 132. Thefirst end 131 of the first portion 130 is coupled to a first shortingpoint GP1 on the system ground plane 112. The second end 132 of thefirst portion 130 is coupled to a second shorting point GP2 on thesystem ground plane 112. A clearance region 180 is formed between thefirst portion 130 of the metal frame 120 and the system ground plane112. In alternative embodiments, if the mobile device 100 furtherincludes a display device 185, the clearance region 180 will be definedbetween the first portion 130 of the metal frame 120 and the displaydevice 185. The clearance region 180 may substantially have a narrow andlong rectangular shape, and it may be positioned between the firstshorting point GP1 and the second shorting point GP2. The length of theclearance region 180 is equal to or slightly shorter than the length ofthe first portion 130. The first portion 130 of the metal frame 120 iscoupled to a feeding point FP. The feeding point FP is positionedbetween the first end 131 and the second end 132 of the first portion130. The feeding point FP is closer to the first shorting point GP1 thanthe second shorting point GP2.

The extension radiation element 150 is made of a metal material. In someembodiments, the metal frame 120 further includes a second portion 140,and the extension radiation element 150 is formed by the second portion140. That is, the extension radiation element 150 and the metal frame120 may be integrally formed. In alternative embodiments, the metalframe 120 does not include the second portion 140, and the extensionradiation element 150 is printed on another FPC or is formed on aplastic supporting element using an LDS (Laser Direct Structuring)technique. The extension radiation element 150 may substantially have anL-shape. In alternative embodiments, the extension radiation element 150has a different shape, so as to meet the requirement of differencefrequencies. Specifically, the extension radiation element 150 has afirst end 151 and a second end 152. The first end 151 of the extensionradiation element 150 is coupled to the feeding point FP. The second end152 of the extension radiation element 150 is an open end, which extendsaway from the first grounding point GP1. A portion of the extensionradiation element 150 is parallel to the first portion 130 of the metalframe 120, and another portion of the extension radiation element 150 isperpendicular to the first portion 130 of the metal frame 120. Theextension radiation element 150 may have a vertical projection which atleast partially overlaps the clearance region 180. In addition, theextension radiation element 150 may have a vertical projection which atleast partially overlaps the system ground plane 112. An antennastructure is formed by the first portion 130 of the metal frame 130 andthe extension radiation element 150. In alternative embodiments, themetal frame 130 of the mobile device 100 includes only the first portion130 without the second portion 140 (i.e., adjustments are made such thatthe antenna structure does not include the extension radiation element150), but it can still have a similar level of performance to that ofthe original antenna structure (including both the first portion 130 andthe second portion 140 or the extension radiation element 150). The RFmodule 199 may be disposed on the system circuit board 110. The RFmodule 199 is coupled to the feeding point FP, so as to excite theaforementioned antenna structure. In some embodiments, the mobile device100 further includes a feeding connection element 190 and an RF signalline 192. The feeding point FP is coupled through the feeding connectionelement 190 and the RF signal line 192 to the RF module 199. Forexample, the feeding connection element 190 may be a 3D(Three-Dimensional) connection structure, which may be implemented witha pogo pin, a metal spring, or a metal screw. The first portion 130 andthe second portion 140 of the metal frame 120 may be both disposed at aside of the mobile device 100. The other portions of the metal frame 120may be selectively distributed over the top, the bottom, and/or anotherside of the mobile device 100. Accordingly, the whole metal frame 120may substantially have a loop shape, and the system circuit board 110may be disposed in a hollow interior of the metal frame 120.

In the embodiment of FIG. 1A and FIG. 1B, the electronic component 160at least includes a power button 161 and/or a volume button 162, but theinvention is not limited thereto. In other embodiments, the electroniccomponent 160 includes fewer or more physical buttons and/or socketswith different functions. The FPC 170 is coupled to the power button 161and the volume button 162 of the electronic component 160. Theelectronic component 160 and the FPC 170 are both adjacent to the firstportion 130 of the metal frame 120. For example, the power button 161and the volume button 162 may be at least partially disposed at anexternal side of the first portion 130 of the metal frame 120(alternatively, the power button 161 and the volume button 162 maypartially extend to an internal side of the first portion 130 of themetal frame 120), and the FPC 170 may be disposed at the internal sideof the first portion 130 of the metal frame 120. The first portion 130of the metal frame 120 may have one or more openings thereon althoughthey are not displayed in FIG. 1A and FIG. 1B. Accordingly, theelectronic component 160 may be coupled through the aforementionedopenings to the FPC 170. The FPC 170 may be further configured to carrysome traces and circuit layouts of control elements.

The extension radiation element 150 has a vertical projection which atleast partially overlaps the FPC 170. For example, the whole verticalprojection of the extension radiation element 150 may be inside the FPC170. In some embodiments, the FPC 170 is further coupled to the systemground plane 112. For example, the FPC 170 may further include an FPCconnector 171 and two bare copper regions 172 and 173. The FPC connector171 and the bare copper regions 172 and 173 may penetrate through thesystem circuit board 110. The FPC connector 171 and the bare copperregions 172 and 173 may be coupled to the system ground plane 112.Specifically, the bare copper region 172 may be adjacent to the firstgrounding point GP1 or may overlap the first grounding point GP1; thebare copper region 173 may be adjacent to the second grounding point GP2or may overlap the second grounding point GP2. With such a design, theelectronic component 160 and the FPC 170 can be integrated with theaforementioned antenna structure, and they are considered as anextension portion of the antenna structure. Accordingly, the electroniccomponent 160 and the FPC 170 do not interfere with the radiationperformance of the antenna structure so much.

In alternative embodiments, a metal layer (or a conductive materiallayer) of the FPC 170 substantially has a C-shape or an L-shape. Themetal layer of the FPC 170 may extend along an outer edge of theclearance region 180, and the vertical projection of the metal layer mayat least partially overlap the clearance region 180.

In some embodiments, the mobile device 100 further includes one or moreother antenna elements (not shown). The other antenna elements may beformed by the other portions of the metal frame 120, and they may bepositioned at the top or the bottom of the mobile device 100. The otherantenna elements may further have one or more cut points. The otherantenna elements may be used as main antennas of the mobile device 100.On the other hand, because the clearance region 180 is relatively small,the aforementioned antenna structure may be used as an auxiliary antennaof the mobile device 100, so as to increase the antenna diversity gainof the mobile device 100. For example, the first shorting point GP1 canbe positioned between the antenna structure and the other antennaelements, so as to enhance the isolation between the other antennaelements and the antenna structure.

FIG. 3 is a diagram of VSWR (Voltage Standing Wave Ratio) of the antennastructure of the mobile device 100 according to an embodiment of theinvention. The horizontal axis represents the operation frequency (MHz),and the vertical axis represents the VSWR. According to the measurementin FIG. 3, the antenna structure of the mobile device 100 can cover alow-frequency band FB1 from 2400 MHz to 2500 MHz, and a high-frequencyband FB2 from 5150 MHz to 5875 MHz. Therefore, the mobile device 100 cansupport at least the dual-band operations of WLAN (Wireless Local AreaNetworks) 2.4 GHz/5 GHz (or Wi-Fi). The above frequency ranges may beadjusted to meet different requirements.

The antenna theory and the element sizes of the mobile device 100 may beas follows. The first portion 130 of the metal frame 120 is excited togenerate the low-frequency band FB1, and the extension radiation element150 (or the second portion 140 of the metal frame 120) is excited togenerate the high-frequency band FB2. The length of the first portion130 (i.e., the length from the first end 131 to the second end 132, orthe length from the first shorting point GP1 to the second shortingpoint GP2) may be substantially equal to 0.5 wavelength (λ/2) of thelow-frequency band FB1. The length of the extension radiation element150 (i.e., the length from the first end 151 to the second end 152, orthe length from the feeding point FP to the second end 152) may besubstantially equal to 0.25 wavelength (λ/4) of the high-frequency bandFB2. A first distance D1 is defined between the feeding point FP and thefirst end 131 of the first portion 130 (or the first shorting pointGP1). A second distance D2 is defined between the feeding point FP andthe second end 132 of the first portion 130 (or the second shortingpoint GP2). The ratio of the second distance D2 to the first distance D1(D2/D1) may be substantially from 4 to 5. For example, the firstdistance D1 may be about 8.5 mm, and the second distance D2 may be about35.5 mm, but they are not limited thereto. The width W3 of the clearanceregion 180 (i.e., the shortest distance between the first portion 130 ofthe metal frame 120 and the system ground plane 112 or the displaydevice 185, wherein the distance between the system ground plane 112 andthe metal frame 120 may be longer than or equal to the distance betweenthe display device 185 and the metal frame 120) may be arranged foradjusting the impedance matching and the bandwidth of the aforementionedantenna structure. If the width W3 of the clearance region 180 becomeslarger, the bandwidth of the low-frequency band FB1 of the antennastructure will become wider; conversely, if the width W3 of theclearance region 180 becomes smaller, the bandwidth of the low-frequencyband FB1 of the antenna structure will become narrower. For example, thewidth W3 may be about 1.5 mm, but it is not limited thereto.Furthermore, the impedance matching of the low-frequency band FB1 isfurther fine-tuned by changing the position of the feeding point FP. Theabove element sizes are calculated and obtained according to manyexperiment results, and they help to optimize the operation performanceof the antenna structure of the mobile device 100. According to thepractical measurement, the radiation efficiency of the antenna structureof the mobile device 100 is higher than 13.6% in both the low-frequencyband FB1 and the high-frequency band FB2. This can meet the requirementsof application of general mobile communication devices.

In the mobile device 100 of the invention, since the metal frame 120 isused as a main radiator of the antenna structure, it can effectivelyprevent the metal frame 120 from negatively affecting the communicationquality of the antenna structure. Furthermore, the antenna structure canbe integrated with the electronic component 160 (e.g., side buttonsand/or sockets) and the FPC 170, and used together with the narrow andsmall clearance region 180, so as to minimize the whole antenna size (aconventional mobile device usually has too small a clearance region atits side to accommodate any antenna structure). In addition, there is nocut point on at least the first portion 130 of the metal frame 120. Sucha design can significantly improve the robustness and the produceappearance of the mobile device 100. The invention can support thecommunication technology including, for example, Wi-Fi and MIMO(Multi-Input and Multi-Output), and therefore it is suitable forapplication in a variety of small-size, wideband mobile communicationdevices.

FIG. 4A is a back view of a mobile device 400 according to an embodimentof the invention. FIG. 4B is a side view of the mobile device 400according to an embodiment of the invention. FIG. 4A and FIG. 4B aresimilar to FIG. 1A and FIG. 1B. The difference between the twoembodiments is that an electronic component 460 of the mobile device 400includes one or more sensing elements 461. The sensing elements 461 andthe FPC 170 are disposed at the internal side of the first portion 130of the metal frame 120. The sensing elements 461 and the FPC 170 arecoupled to each other. At this time, there is no opening designed on atleast the first portion 130 of the metal frame 120 due to thearrangements of the sensing elements 461. Each of the sensing elements461 may be a pressure sensor for detecting the pressing state of thefirst portion 130 of the metal frame 120, which is pressed by a user.Similarly, the aforementioned antenna structure can be integrated withthe electronic component 460 and the FPC 170, and used together with thenarrow and small clearance region 180, so as to minimize the wholeantenna size. Other features of the mobile device 400 of FIG. 4A andFIG. 4B are similar to those of the mobile device 100 of FIG. 1A, FIG.1B, and FIG. 2. Accordingly, the two embodiments can achieve similarlevels of performance.

The following embodiments will introduce a variety of differentconfigurations of the invention. It should be understood that thesefigures and descriptions are merely exemplary, rather than limitationsof the invention.

FIG. 5 is a perspective view of a mobile device 500 according to anembodiment of the invention. In the embodiment of FIG. 5, the mobiledevice 500 further includes a main camera 510 and a non-metal back cover520. The main camera 510 is embedded in the non-metal back cover 520. Asmentioned above, the antenna structure can be formed by the firstportion 130 of the metal frame 120 (the antenna structure may be formedat a first position 501 or a second position 502), and the antennastructure can be integrated with the electronic components 160 (e.g.,the aforementioned side buttons 161 and 162 or the aforementionedsensing elements 461) and the FPC. A boundary 525 between the non-metalback cover 520 and the metal frame 120 is positioned at a back side ofthe mobile device 500. In other embodiments, the non-metal back cover520 extends from the back side to a lateral side of the mobile device500, such that the boundary 525 between the non-metal back cover 520 andthe metal frame 120 is positioned at the lateral side of the mobiledevice 500. The other portions of the metal frame 120 (except for thefirst portion 130 and the second portion 140) may have one or more cutpoints 126 for fine-tuning the impedance matching and the resonantfrequency of the other antenna elements.

FIG. 6 is a perspective view of a mobile device 600 according to anembodiment of the invention. In the embodiment of FIG. 6, the mobiledevice 600 further includes a back cover 620. As mentioned above, theantenna structure can be formed by the first portion 130 of the metalframe 120 (the antenna structure may be formed at a first position 501or a second position 502), and the antenna structure can be integratedwith the electronic components 160 (e.g., the aforementioned sidebuttons 161 and 162 or the aforementioned sensing elements 461) and theFPC. The back cover 620 includes a metal portion 621 and a non-metalportion 622. The metal portion 621 substantially has a rectangularshape, and the non-metal portion 622 substantially has a loop shape,such that the metal portion 621 is completely surrounded by thenon-metal portion 622. The non-metal portion 622 of the back cover 620can prevent the metal portion 621 from directly touching the firstportion 130 of the metal frame 120. Accordingly, good communicationquality of the antenna structure can be maintained.

FIG. 7 is a perspective view of a mobile device 700 according to anembodiment of the invention. In the embodiment of FIG. 7, the mobiledevice 700 further includes a back cover 720. As mentioned above, theantenna structure can be formed by the first portion 130 of the metalframe 120 (the antenna structure may be formed at a first position 501or a second position 502), and the antenna structure can be integratedwith the electronic components 160 (e.g., the aforementioned sidebuttons 161 and 162 or the aforementioned sensing elements 461) and theFPC. The back cover 720 includes a metal portion 721, a first non-metalportion 722, and a second non-metal portion 723. The metal portion 721is positioned between the first non-metal portion 722 and the secondnon-metal portion 723, and is configured to completely separate thefirst non-metal portion 722 from the second non-metal portion 723. Thefirst non-metal portion 722 of the back cover 720 can prevent the metalportion 721 from directly touching the first portion 130 of the metalframe 120. Accordingly, good communication quality of the antennastructure can be maintained. In some embodiments, the mobile device 700uses a spray and coat process to reduce the visual difference betweenthe metal portion 721 and each of the first non-metal portion 722 andthe second non-metal portion 723, thereby improving the appearanceconsistency of the mobile device 700.

FIG. 8 is a perspective view of a mobile device 800 according to anembodiment of the invention. In the embodiment of FIG. 8, the mobiledevice 800 further includes a back cover 820. As mentioned above, theantenna structure can be formed by the first portion 130 of the metalframe 120 (the antenna structure may be formed at a first position 501or a second position 502), and the antenna structure can be integratedwith the electronic components 160 (e.g., the aforementioned sidebuttons 161 and 162 or the aforementioned sensing elements 461) and theFPC. The back cover 820 includes a metal portion 821, a first non-metalportion 822, a second non-metal portion 823, and a third non-metalportion 824. The metal portion 821 is positioned between the firstnon-metal portion 822, the second non-metal portion 823, and the thirdnon-metal portion 824. Specifically, the metal portion 821 can make thefirst non-metal portion 822, the second non-metal portion 823, and thethird non-metal portion 824 completely separate from each other. Incomparison to the embodiment of FIG. 7, the first non-metal portion 822,the second non-metal portion 823, and the third non-metal portion 824 ofthe back cover 820 have different shapes. For example, the firstnon-metal portion 822 may substantially have a U-shape, the secondnon-metal portion 823 may substantially have a rectangular shape, andthe third non-metal portion 824 may substantially have a thin and longstraight-line shape. The first non-metal portion 822 of the back cover820 can prevent the metal portion 821 from directly touching the firstportion 130 of the metal frame 120. Accordingly, good communicationquality of the antenna structure can be maintained. In some embodiments,the mobile device 800 uses a spray and coat process to reduce the visualdifference between the metal portion 821 and each of the first non-metalportion 822, the second non-metal portion 823, and the third non-metalportion 824, thereby improving the appearance consistency of the mobiledevice 800. It should be noted that aforementioned back cover and metalframe may be the same mechanism element (both are integrally formed), ormay be two independent elements which are manufactured independently.

FIG. 9 is a flowchart of a method for manufacturing a mobile deviceaccording to an embodiment of the invention. The manufacturing methodincludes at least the following steps. In step S910, a first circuitboard, a metal frame, an extension radiation element, an electroniccomponent, a second circuit board, and an RF (Radio Frequency) moduleare provided. The first circuit board includes a system ground plane.The metal frame includes a first portion. The electronic component andthe second circuit board are adjacent to the first portion. In stepS920, the first portion is coupled to the system ground plane. In stepS930, a clearance region is formed between the first portion and thesystem ground plane. In step S940, the first portion and the extensionradiation element are coupled to a feeding point, such that an antennastructure is formed by the first portion and the extension radiationelement. In step S950, the second circuit board is coupled to theelectronic component. In step S960, the RF module is coupled to thefeeding point, so as to excite the antenna structure. It should beunderstood that the above steps are not required to be performed inorder, and any one or more device features of FIGS. 1 to 8 may beapplied to the manufacturing method of the mobile device of FIG. 9.

Note that the above element sizes, element shapes, and frequency rangesare not limitations of the invention. An antenna designer can fine-tunethese settings or values according to different requirements. It shouldbe understood that the mobile device and the manufacturing method of theinvention are not limited to the configurations of FIGS. 1-9. Theinvention may include any one or more features of any one or moreembodiments of FIGS. 1-9. In other words, not all of the featuresdisplayed in the figures should be implemented in the mobile device andthe manufacturing method of the invention.

Use of ordinal terms such as “first”, “second”, “third”, etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having the same name (but for use of the ordinalterm) to distinguish the claim elements.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention. It isintended that the standard and examples be considered as exemplary only,with a true scope of the disclosed embodiments being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A mobile device, comprising: a first circuitboard, comprising a system ground plane; a metal frame, at leastcomprising a first portion, wherein the first portion is electricallycoupled to the system ground plane and a feeding point, and wherein anantenna structure is formed by the first portion and the feeding point;an electronic component; a second circuit board, electrically coupled tothe electronic component, wherein the electronic component and thesecond circuit board are adjacent to the first portion; and an RF (RadioFrequency) module, electrically coupled to the feeding point, so as toexcite the antenna structure.
 2. The mobile device as claimed in claim1, wherein the first portion has a first end and a second end, a firstend of the first portion is coupled to a first shorting point on thesystem ground plane, and a second end of the first portion is coupled toa second shorting point on the system ground plane.
 3. The mobile deviceas claimed in claim 2, wherein a clearance region is formed between thefirst portion and the system ground plane.
 4. The mobile device asclaimed in claim 3, wherein the clearance region is positioned betweenthe first shorting point and the second shorting point.
 5. The mobiledevice as claimed in claim 3, wherein the metal frame further comprisesan extension element which is electrically coupled to the feeding point.6. The mobile device as claimed in claim 5, wherein the metal framefurther comprises a second portion, and the extension element is formedby the second portion.
 7. The mobile device as claimed in claim 5,wherein the extension element is printed on a flexible printed circuitboard.
 8. The mobile device as claimed in claim 1, wherein the firstcircuit board is a system circuit board, and the second circuit board isa flexible printed circuit board.
 9. The mobile device as claimed inclaim 5, wherein the extension element has a vertical projection whichat least partially overlaps the second circuit board.
 10. The mobiledevice as claimed in claim 5, wherein the extension element has avertical projection which at least partially overlaps the clearanceregion.
 11. The mobile device as claimed in claim 1, further comprising:a feeding connection element; and an RF signal line, wherein the feedingpoint is coupled through the feeding connection element and the RFsignal line to the RF module.
 12. The mobile device as claimed in claim1, wherein the second circuit board is further electrically coupled tothe system ground plane.
 13. The mobile device as claimed in claim 1,wherein the second circuit board is disposed on the first circuit board.14. The mobile device as claimed in claim 5, wherein the first portionis excited to generate the low-frequency band, and the extension elementis excited to generate the high-frequency band.
 15. The mobile device asclaimed in claim 11, wherein the feeding connection element is coupledto the extension element.
 16. The mobile device as claimed in claim 1,wherein the electronic component comprises a power button and/or avolume button disposed in an opening of the first portion of the metalframe.
 17. The mobile device as claimed in claim 16, wherein the powerbutton and the volume button are at least partially disposed at anexternal side of the first portion of the metal frame.
 18. The mobiledevice as claimed in claim 16, wherein the power button and the volumebutton at least partially extend to an internal side of the firstportion of the metal frame.
 19. The mobile device as claimed in claim 1,wherein the electronic component comprises one or more sensing elements.20. The mobile device as claimed in claim 19, wherein the sensingelements are disposed at an internal side of the first portion.
 21. Themobile device as claimed in claim 16, wherein there is no cut pointformed on the first portion of the metal frame, and the opening is notequivalent to a cut point.
 22. The mobile device as claimed in claim 1,further comprising: a main camera; and a non-metal back cover, whereinthe main camera is embedded in the non-metal back cover.
 23. The mobiledevice as claimed in claim 22, wherein a boundary between the non-metalback cover and the metal frame is positioned at a back side or a lateralside of the mobile device.
 24. The mobile device as claimed in claim 22,wherein the metal frame further has one or more cut points.